Keratoacanthoma is a self limiting, epithelial prolieration with a strong clinical and histopathologic similarity to well differentiated squamous carcinoma. Some consider it as a  Cutaneous lesion presumably arise from the infundibulum of hair follicles. Intra Oral lesions are rare but have been seen.

It is a common low grade malignancy that origanates in the pilo sebaseous glands. It is also called as the “Self healing  carcinoma”

It resembles Squamous cell carcinoma, and considered a variant of invasive squamous cell carcinoma.


  • Self healing carcinoma
  • Molluscum pseudocarcinomatosum
  • Molluscum sabecum
  • Verrucoma
Differential diagnosis:
  • Actin keratosis
  • Molluscum contagiosum
  • Muir-Torre Syndrome
  • Squamous cell carcinoma
  • Verrucous
  • Exposure to sunlight
  • Exposure to Pitch, tar.
  • Trauma
  • Human Papilloma Virus
  • Genetic factors
  • Immunocompramised status
Clinical  Features:
Clinically it appears as a painless well circumscribed dome or bud shaped tumor of 1-2 cm in diameter with a keratin crater at the center. The tumor begins as a small nodule that grows rapidly and within 4-8
  1. Age: All ages are equally affected.
  2. Sex: M>F
  3. Race: White>Black
  4. Common sites on Body: Seen mostly in sun exposed areas- Face, neck, dorsum of upper limb.
  5. Common sites on face: Lips, Vermillion border.
  6. Lesions are Solitary, Firm, Round, Skin coloured (or) Reddish papules which progress to Dome shaped nodules with a shiny surface and a central crateriform ulceration (or) Keratin Plug that may project like a Horn.
  7. Lesions: Elevated Umbilicated (or) Crateriform with a depressed central core.
  8. Size: 1 – 1.5 cm in diameter.
  9. It is a painful lesion seen with Lymphadenopathy.
Course of the Lesion:
Small firm nodule –> Full size in 4 to 8 weeks –> (6 – 8 weeks in a static stage) –> Regrussion by expulsion of keratin.
Histological features:
  1. Hyperplastic squamous epithelium can be seen growing into the underlying connective tissue.
  2. Surface is covered be Ortho keratinized or Parakeratinized epithelium with central plugging.
  3. At the margins the normal epthelium is elevated to the central portion of the crater, then an abrupt change in the normal epithelium occurs as the hyperplastic acanthomatous epithelium is reached.
  4. Borders / Margins are very important for diagnosis.
  5. At margins islands of epithelium appear invading the deep leading margin of the tumor.
  6. Pseudocarcinomatous infiltration typically presents a smoother, regular well demarcated front that does not extend beyond the level of sweat glands.
  7. Connective tissue shows chronic inflamatory cell infiltration.
Histology of Keratoacanthoma

Histology of Keratoacanthoma

Treatment and Prognosis:
  • Surgical Exision.
  • Aggressive therapy on recurrance.
  • Recurrance is rare.
  • Prognosis is good.
  • May lead to skin cancer in future.

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